Fail Safe Light

Hi, Just purchased a 2004 1.6 petrol C-MAX. All was fine and then the red warning light came on and we experienced loss of power between gear shifts. This came on and off indiscriminately. It wasn't obvious to our garage what was wrong, however their computer was registering issues with the throttle. The garage owner advised that it was probably ok to drive as the red warning light is supposed to indicate that the engine is overheating (it wasn't). The other warning light finally came on (orange) and on one journey the engine just cut out without any warning luckily I didn't have an accident. It happened again a few times after that. We have had work costing over £200 carried out to change the throttle sensor on the pedal. We've been told there are two other throttle sensors which may also need to be changed at a further cost of £350. If I knew this would fix the problem then I would gladly have the work done.
There has been an improvement with the first lot of work but the red warning light still comes on very occasionally.
Has anyone come across this problem and had resolution ?
many thanks